However, the more you understand about what's coming next, the more in control you'll feel. While every clinic's protocol will be slightly different and treatments are adjusted for a couple's individual needs, here is a step-by-step breakdown of what generally takes place during in vitro fertilization, as well as information on the risks, costs, and what’s next if your IVF treatment cycle fails.
Mild IVF[64] is a method where a small dose of ovarian stimulating drugs are used for a short duration during a woman's natural cycle aimed at producing 2–7 eggs and creating healthy embryos. This method appears to be an advance in the field to reduce complications and side-effects for women and it is aimed at quality, and not quantity of eggs and embryos. One study comparing a mild treatment (mild ovarian stimulation with GnRH antagonist co-treatment combined with single embryo transfer) to a standard treatment (stimulation with a GnRH agonist long-protocol and transfer of two embryos) came to the result that the proportions of cumulative pregnancies that resulted in term live birth after 1 year were 43.4% with mild treatment and 44.7% with standard treatment.[65] Mild IVF can be cheaper than conventional IVF and with a significantly reduced risk of multiple gestation and OHSS.[66]

Around one in 7 couples that require artificial reproductive treatment (ART) have "unexplained" infertility and doctors often first use approaches like ensuring the female partner's ovulation occurs at the same time as natural sex or artificial insemination/intrauterine insemination (IUI). They may then recommend IVF where thousands of the male partner's best sperm are purified and incubated with the egg — this is the preferred initial ART procedure in cases of "unexplained" infertility.
The Rand Consulting Group has estimated there to be 400,000 frozen embryos in the United States in 2006.[83] The advantage is that patients who fail to conceive may become pregnant using such embryos without having to go through a full IVF cycle. Or, if pregnancy occurred, they could return later for another pregnancy. Spare oocytes or embryos resulting from fertility treatments may be used for oocyte donation or embryo donation to another woman or couple, and embryos may be created, frozen and stored specifically for transfer and donation by using donor eggs and sperm. Also, oocyte cryopreservation can be used for women who are likely to lose their ovarian reserve due to undergoing chemotherapy.[84]
Sometimes problems getting pregnant for a second or subsequent time are related to a complication that occurred in a prior pregnancy or prior to delivery (damage to the uterus, for instance). But most often, secondary infertility is caused by the same factors that would cause primary infertility — issues like advanced age, obesity, ovulation problems and so on.

It is extremely difficult for those with unexplained infertility to know when to stop looking for a cause, to say “enough is enough.” You may feel you are entering a state of limbo. You may feel stuck unable to grieve and get on with other options because you hang on to those slender threads of hope that the cause of your infertility will be revealed in the next test or treatment. Your sadness may intensify as time passes and you find no medical or emotional resolution. Consider finding a Support Group or Mental Health Professional in your area.

A woman's age is a major factor in the success of IVF for any couple. For instance, a woman who is under age 35 and undergoes IVF has a 39.6% chance of having a baby, while a woman over age 40 has an 11.5% chance. However, the CDC recently found that the success rate is increasing in every age group as the techniques are refined and doctors become more experienced.
SART, in conjunction with, The American Society for Reproductive Medicine (ASRM), has published guidelines for the recommended number of embryos to transfer (add to link). These guidelines are based on SART-sponsored research which continually evaluates success rates around the country.  This helps to determine the optimal number of embryos to transfer, based on specific patient characteristics, like age and history of prior IVF.  Patients may require several cycles of treatment to have a baby. Success rates remain fairly constant over several cycles, but may vary greatly between individuals.  
Ovarian reserve testing. To determine the quantity and quality of your eggs, your doctor might test the concentration of follicle-stimulating hormone (FSH), estradiol (estrogen) and anti-mullerian hormone in your blood during the first few days of your menstrual cycle. Test results, often used together with an ultrasound of your ovaries, can help predict how your ovaries will respond to fertility medication.
When the ovarian follicles have reached a certain degree of development, induction of final oocyte maturation is performed, generally by an injection of human chorionic gonadotropin (hCG). Commonly, this is known as the "trigger shot."[67] hCG acts as an analogue of luteinising hormone, and ovulation would occur between 38 and 40 hours after a single HCG injection,[68] but the egg retrieval is performed at a time usually between 34 and 36 hours after hCG injection, that is, just prior to when the follicles would rupture. This avails for scheduling the egg retrieval procedure at a time where the eggs are fully mature. HCG injection confers a risk of ovarian hyperstimulation syndrome. Using a GnRH agonist instead of hCG eliminates most of the risk of ovarian hyperstimulation syndrome, but with a reduced delivery rate if the embryos are transferred fresh.[69] For this reason, many centers will freeze all oocytes or embryos following agonist trigger.
Fertilization. An embryologist (a scientist who specializes in eggs, sperm, and embryos) will examine your eggs before combining them with your partner's sperm and incubating them overnight. Fertilization usually happens during this time, but eggs that aren't normal may not be fertilized. (If sperm quality is poor, or if fertilization was unsuccessful during previous IVF cycles, your doctor may recommend using a technique called intracytoplasmic sperm injection (ICSI). With ICSI, a single sperm is injected directly into each mature egg.)
Egg retrieval and sperm collection – Egg retrieval happens 35 hours after the trigger shot. It is done under light anesthesia and takes just 5-10 minutes. During retrieval, a tiny hollow needle is pierced through the vaginal wall towards an ovary. At this point, the fluid that contains the developed eggs is drained from the follicles and immediately taken to the IVF laboratory, where they will be fertilized and developed. Sperm is collected the same day as the procedure by ejaculation into a sterile specimen container, frozen ahead of time, via a donor, or through more advanced sperm retrieval procedures. Next, the sperm is washed, placed in a solution similar to the fallopian tubes, and used for fertilization.
For five to six days following fertilization, the developing embryos are cultured in the laboratory until the blastocyst stage of development has been reached. This represents growth of about 200 cells. We at RMA culture embryos exclusively to the blastocyst stage, because published data demonstrates that extended embryo culture results in improved implantation rates and pregnancy outcomes. This means we will never do an embryo biopsy – or an embryo transfer – at three days, or anything less than the blastocyst stage.
When weighing the options, the pros and cons of intrauterine insemination (IUI) and in vitro fertilization (IVF) will, of course, be explored fully in discussion with your physician. In general terms, you can expect IUI to be a simpler process, less invasive, and lower cost. Some fertility specialists recommend attempting one or more cycles of artificial insemination before moving to IVF but this does not apply to everyone. For example, for an older woman, to try artificial insemination first may take up valuable time and the recommendation could well be to move straight to IVF. But before you can compare the two treatments, you need to know what exactly you could expect from IVF.

In IUI, this natural sequence of events is given some assistance. A sample of sperm is prepared in the laboratory so that only the best moving sperm are concentrated together. This sperm is then deposited directly into the uterus without having to swim there on its own, which can be challenging, especially if the sperm do not swim well. IUI places a higher concentration of moving sperm closer to the ovulated egg. Often a woman will have taken medication prior to the IUI procedure to ensure she will ovulate around the time of the procedure, so egg and sperm can meet.
Sometimes problems getting pregnant for a second or subsequent time are related to a complication that occurred in a prior pregnancy or prior to delivery (damage to the uterus, for instance). But most often, secondary infertility is caused by the same factors that would cause primary infertility — issues like advanced age, obesity, ovulation problems and so on.